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Author Topic: More UEFI madness  (Read 507 times)

Offline PDP-8

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More UEFI madness
« on: July 12, 2019, 03:57:06 PM »
Just so one knows why I'm going crazy about UEFI, and in particular UEFI-ONLY.

The standard is that there is no standard in practice.  And why some techniques work, and don't *when they should*.

I'm about to go back to my IMSAI 8080 and start flipping switches again. :)

This may be in bad taste reposting from a developer forum, but it included as just an example of why I *REALLY* want to leave automated booloader building to either devs or 3rd parties devoted to the craft:

Code: [Select]
In theory they work and in practice in 99% of the cases when booting
internal hard drives. My preferred boot configuration on all PC systems
are GPT partitioned drives with a partition markes EFI system and one
marked legacy boot (might apply to the same partition) and using
gptmbr.bin from syslinux to boot.

In practice there are some early EFIs (ca. 2007 to 2010) that are
disguised as BIOS that ignore the 448 byte boot block on USB drives and
instead look for a MBR partition table and one partition marked as
active. Because of the protective MBR they won't boot a GPT partitioned
stick. Something similar applies to many 32 bit UEFIs (cheap Intel
tablets and netbooks). To boot from external media those expect a single
partition drive, MBR partition table and the partition flagged as (EFI
system partition) containing all the boot files. This might violate the
UEFI standards, but I guess since Windows bootable USB drives use
exactly this single partition MBR layout, no one cares in practice.

Yours,
Mattias

--
Mattias Schlenker - Freier IT-Fachredakteur und -autor

So I'm not crazy after all running TC on modern hardware!  I'm just 0.00001% of the Linux demographic crazy enough to *like* it.!
That's a UNIX book! - cool  -- Garth

Offline coreplayer2

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More UEFI madness
« Reply #1 on: July 12, 2019, 05:36:19 PM »
Yes but I think he’s talking about first generation EFI most likely the first Apple 32bit EFI which are built with CSM enabled by default for CD Compatibility, I don’t think qualifies as Modern UEFI..
Apples’s original EFI is as old as the dinosaur, whilst modern PC manufactures take liberties with the features their BIOS/Firmware supports  not with EFI standards IMO




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« Last Edit: July 12, 2019, 05:42:29 PM by coreplayer2 »